Electrically-heated vessel.



H. MIETH.

. BLBGTRIGALLY HBATED VESSEL.

APPLICATION FILED JAN. 3, 1911.

Patented May 23, 1911.

HERMAN MIETH, 0F VANCOUVER, :BRITISH COLUMBIA', CANADA.

ELECTRICALLY-HEATEID VESSEL.

Specification of 'Letters Eatent. Paytnted May 23, 1911, Application filed January 3, 1311.

Serial No. 600,410.`

To all whom t may concern:

Be it known that I, HERMAN MIETH, a citizen of the United States of America, re-

siding at Vancouver, in the Province of- British Columbia, Canada, have invented a new and useful Electrically-Heated Vessel, of which the following is a specification.

This invention relates to an electrically heated water vessel for the heating of lwater or other liquid.

Attempts have previously been made to heat liquid by means of electricity either b means of an immersed resistance coil in th liquid itself in which case a considerable loss is incurred by short circuiting between the coils through the liquid, and this system is also open to object-ion in that the current is such as will fuse the xcoil if it is not immersed in the liquid. Another system in common use is to connect what is termed a heating pad to the under side of the vessel, the coil in this case being secured between layers of insulating material but this construction 'does not enable the coil to be in close contact with the wall of the vessel and much of the heat is, on this account, lost as it may pass by radiation from the other side of the pad. These defects I have overcome in the invention which is the subject of this application by inclosing the heating coil between an outer and inner casing forming the bottom and sides of the vessel by which construction I am enabled to place the coil on very thin insulation in contact with the inner wall of the vessel and by filling in between the coil with an electrical non-conducting cement by which means the adjacent coils are el'iiciently insulated from one another and by providing a heat non-conducting layer inside of the outer casing of the vessel no appreciable amount of the heatV generated in the coil may pass other than through the innerwall of the casing where it is imparted to the liquid within it.

The invention is particularly described in the following specification, reference being mad-e to the drawings by which it is accompanied, in which:

Figure 1 is a vertical section through a vessel having my heating provision, Fig. 2 is a top plan view of the vessel, part of the handle being broken off, Fig. 3, an enlarged detail of a section of the coil within its insulation and casing.

In these drawings 2 represents the inner and 3 the outer wall or casing of the coil which casings form the4 sidesand bottom of the vessel. The wires 4: which form the coil are preferably wound double, as shown in Fig. 2, and commencing at the center of the bottom extend outward to the cylindrical wall up which they are coiled to a short distance from the top where they are connected tothe terminals 5 and 6. The surfaces of the inner casing 2 on which the coil is tightly wound is first covered with -athin layer 7 of efficient insulation such as a vitreous enamel or sheet mica and the coil is tightly wound on it. Thereafter the interspace between thecoils is filled inl with an electrical non-conducting cement 8' that will efi'ectually insulate the coils from one another and between the wires of the cils so insulated and the outer casing wall 3 of the vessel is placed a layer 9 of heat non-conducting material. No particular care need be taken that this heat non-conducting layer is tightly packed within the casing as any air space will itself act as a non-conductor. In a vessel so constructed the wires of the coil are effectively insulated not only from the inner casing 2 of the vessel but also from one another and the coils are as close as practicable to the inner wall consistent with such insulation and any heat generated in the coil must pass through the inner wall of the vessel as the heat non-conducting layer 9 will prevent any passage outward. Furthermore the coil and its insulation is effectively protected against possible injury to which it might be readily exposed in a vessel of this character. The construction also lends itself to the formation of a light and strong vessel as the inner casing 2 may be of very thin aluminium as it will be backed up and strengthened by the coil and insulating layers and thereafter by the outer wall of the casing 2 which may be of steel or other suitable metal.

I4 am aware that prior to my invention electrical resistance coils have been used for generating heat and that such have been inclosed between flat layers of insulating Y material to form a heating pad `so that I' heat insulating lining for said outer shell and spaced from said inner shell, a heating coil wound around said inner shell within the space between the shells, and a cement filler in said yspace between said shells to unite the same and embed said heating coil.

2. An electrically heated Ivessel, comprising in combination, an inner metal lining forming the vessel, a layer et thin insulation on the outer side of the lining, a wire coil on the insulation, insulating c'ement filling the interspaces between the coils of the wire, a layer of heat non-conducting material on the outside oi the coil and an outer casing inclosing the coil and means for connecting the terminals of 'the coil to an external circuit said cement extending from said layer of thin insulation to said layerof heat nonconducting material.

3. An electrically heated Vessel, comprising in combination, an inner metal lining forming the containing -vessel, a thin layer of insulating material on the outside of the lining, a coil of wire in close contact with the insulalting layer, insulating cement lilling the interspace between the coils of the wire and covering them, a layer of heat nonconducting materiel on the outer side of the insulated coil, a metal casing inclosing the coil and means for connecting the terminals oit the coil to an external circuit.

4. An electrically heated lvessel that comprises an inner and outer cup like shell7 each of said shells having' a flat bottom, said inner shell being ot a smaller sise 'than said outer shell to leave a space between the shells, an electrically insulating coating on the outside of said inner shell, a heat insulating lining on the inside of said outer shell, a cement i'iller in the space between said shells to unite said covering and lining, and

a resistance coil wound around said inner shell and embedded in said liller, said coil consisting of an endless loop wound in a double spiral commencing at substantially the geometric center of the bottoms of said shells and then extending in a 'liat spiral over the bottom of the inner shell and then extending in a tubular spiral around the side wall of said inner shell with 'the ends of said loop terminating adjacent to the upper edges oi' said shells, and means for securing the terminals of an electric circuit to said coil ends.

ln testimony whereof l have signed my naine to this specification in the presence of two subscribing witnesses.

HERMAN MIETH.

1Witnesses:

RownAND BRrr'iAIN, lJVM. S. SoU'rAn. 

